build: fixed target dependency issues

The tests and tools targets depend on libraries generated by the src
target. Adding as dependency at the Makefile inside these respective
folders is not enough since libseccomp uses recursive make.

Signed-off-by: Thiago Marcos P. Santos <thiago.santos@intel.com>
Signed-off-by: Paul Moore <pmoore@redhat.com>

Makefile

@@ -71,7 +71,15 @@ $(VERSION_HDR): version_info.mk
 	echo "#define VERSION_RELEASE \"$(VERSION_RELEASE)\"" >> $$hdr; \
 	echo "#endif" >> $$hdr;
 
-$(SUBDIRS_BUILD): $(VERSION_HDR) $(CONFIGS)
+src: $(VERSION_HDR) $(CONFIGS)
+	@echo "INFO: building in directory $@/ ..."
+	@$(MAKE) -s -C $@
+
+tests: src
+	@echo "INFO: building in directory $@/ ..."
+	@$(MAKE) -s -C $@
+
+tools: src
 	@echo "INFO: building in directory $@/ ..."
 	@$(MAKE) -s -C $@